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Virtual Colonoscopy - Topic Overview

How is it done?

Virtual colonoscopy may be done in a doctor's office, clinic, or a hospital. The test is most often done by a doctor who specializes in performing and interpreting diagnostic imaging tests (radiologist). The doctor may also have an assistant.

You will need to take off most of your clothes. You will be given a gown to wear during the test.

First, you will be asked to lie on your back. Air (or in some cases, carbon dioxide) will be used to expand your colon. This helps the doctor see all parts of your colon. The air is added using a tube placed in your anus. It may be uncomfortable when the air is put into your colon. You may be given medicine to help the muscles in your colon relax.

You will be asked to hold your breath while the pictures of your colon are being taken. If you can't hold your breath for the whole time, the doctor may need to take pictures a couple times in order to get the whole colon. You may be asked to roll over and lie on your stomach. The doctor will ask you to hold your breath again and pictures will be taken with you lying in this position.

The test usually takes about 15 to 30 minutes.

How does a virtual colonoscopy differ from a regular colonoscopy?

Virtual colonoscopy has advantages and disadvantages compared to a regular colonoscopy.


  • Virtual colonoscopy is less invasive, safer, and takes less time than a regular colonoscopy.
  • A thin tube to insert air into the colon is placed in the rectum rather than a long flexible tube that is moved up your colon. (But there is usually some discomfort when the air is inserted.)
  • No medicine to relax or sedate you is needed, so you will be able to drive yourself home and resume normal activities.


  • Virtual colonoscopy may not show polyps smaller than 10 mm (0.4 in.).
  • You will need to hold your breath for short periods of time while the computed tomography (CT) scanner takes pictures of your colon. CT scanning will need to be done twice: once while you lie on your back and then again while you lie on your stomach.
  • Virtual colonoscopy is not covered by all health insurance plans. Check with your insurance plan before having the test.
  • There is a small chance of developing cancer from having some types of CT scans.1 If you are concerned about this risk, talk to your doctor about the amount of radiation this test may give you or your child and confirm that the test is needed.
  • There is a slight risk that the CT scan can interfere with implanted or external medical devices. Examples of medical devices include pacemakers, insulin pumps, defibrillators, and neurostimulators.
  • If a polyp is found, regular colonoscopy will be needed to confirm the diagnosis and remove the polyp so it can be looked at under a microscope. You will need to do another bowel preparation before the colonoscopy.

WebMD Medical Reference from Healthwise

Last Updated: December 07, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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